from keras import backend as K
from keras.layers import Layer


class MyLayer(Layer):
    def __init__(self, output_dim, **kwargs):
        self.output_dim = output_dim
        super(MyLayer, self).__init__(**kwargs)

    def build(self, input_shape):
        # 为该层创建一个可训练的权重
        self.kernel = self.add_weight(
            name="kernel",
            shape=(input_shape[1], self.output_dim),
            initializer="uniform",
            trainable=True,
        )
        super(MyLayer, self).build(input_shape)  # 一定要在最后调用它

    def call(self, x):
        return K.dot(x, self.kernel)

    def compute_output_shape(self, input_shape):
        return (input_shape[0], self.output_dim)
